However, that hasn't stopped critics from questioning the casting decision and clogging up Rowling's mentions with senseless vitriol. "With my experience of social media, I thought that idiots were going to idiot," Rowling told The Observer while promoting Cursed Child, which opens in previews this week. "What can you say? That's the way the world is. Noma was chosen because she was the best actress for the job."

It's unfortunate that blatant racism is "the way the world is," and it's even more disheartening that so-called fans couldn’t visualize a non-white hero of the story. But that's why Dumezweni's casting is all the more important.

"I had a bunch of racists telling me that because Hermione ‘turned white' -- that is, lost color from her face after a shock -- that she must be a white woman, which I have a great deal of difficulty with," she said. "But I decided not to get too agitated about it and simply state quite firmly that Hermione can be a black woman with my absolute blessing and enthusiasm."